In the conventional manufacturing process of a knitted bag, the raw material is firstly knitted into a double-layered material strip which has upper and lower layers and is seamless on both sides so as to form a tubular material strip. The double-layered material strip is then printed by techniques such as rolling, etc., sealed and cut into pieces, thus forming a knitted bag with two seamless sides.
In the above-manufactured knitted bag, the material should be printed with text on both sides and graph on its upper/lower surface before the sealing and cutting process. The printing process is carried out in such a way that the upper surface has been printed with text on one side (for example, the right side) and graph on another side (for example, the left side); and the lower surface has been printed in reversed order (that is, text on the left side and graph on the right side). Then the material strip is shifted such that the graphs are shifted to central portions of the upper/lower surface while one half of the text appears on each side of the upper/lower surface. Finally, the material strip, after the shift operation, is subjected to the sealing and cutting process to form the knitted bag.
In the above manufacturing steps, the printing of text and graph onto the material strip is not difficult; however, the shift process is cumbersome for the manufacturer. More particularly, to carry out the shift process, the folded material strip must first be unfolded and then the upper surface may be shifted laterally such that the graph is shifted to the central part and the text appears with one half on each side, while the lower surface is subjected to a similar shift process, but in reversed direction. After the shift process, the material strip is pressed to form a lamina-like strip with text and graph arranged in the desired position. The above-described shift process is carried out generally manually, thus being time-consuming and cumbersome.